Researchers studying the genetic makeup of the monkeypox virus said the virus appears to have mutated far, far more than one would normally expect.
The work was described in a new study published in the journal natural medicine. As part of the study, Portuguese researchers collected a total of 15 monkeypox virus sequences – mostly from Portugal – and reconstructed their genetic data.
Monkeypox is a rare disease thought to originate in animals. It belongs to the same virus family as smallpox. Usually monkeypox is localized to countries in West and Central Africa, but this year saw the first multi-country outbreak including cases with no known link to West or Central Africa with more of 3,300 cases reported on Friday.
The virus can be transmitted between people through close contact with lesions, bodily fluids, respiratory droplets – such as face-to-face contact – and contaminated materials. The current outbreak has introduced uncertainty as to exactly how the virus is spreading, with transmission much higher than normal.
In the latest study, the researchers found about 50 genetic variations in the viruses they studied compared to those in 2018 and 2019. This, they said, “is much more than one might expect. expect given previous estimates” of the mutation rate of the orthopoxviruses of which monkeypox is a type—between six and 12 times higher.
These large genetic variations could suggest “accelerated evolution”.
“Our data reveal additional clues to ongoing viral evolution and potential human adaptation,” the team wrote, adding that they had identified proteins known to interact with people’s immune systems. However, further studies will be needed to learn more about the potential role they might play in adapting the monkeypox virus for human spread.
João Paulo Gomes, head of the genomics and bioinformatics unit at the National Institute of Health in Portugal, co-author of the study, said it is unclear whether the mutations contributed to increased transmissibility between people.
“We don’t know,” he said Newsweek. “We just know that those 50 extra mutations were quite unexpected.
“Considering that this 2022 monkeypox virus is likely a descendant of that from the 2017 outbreak in Nigeria, one would not expect more than five to 10 additional mutations instead of the approximately 50 mutations observed. We hope that now specialized groups will carry out experiments in the laboratory. in order to understand whether this 2022 virus has increased its transmissibility.”
Another notable finding from the study is that most of the mutations are of a particular type that could have been introduced by a human defense mechanism called APOBEC3, which works by introducing mutations into viruses in order to prevent them from working properly. , said Pam Vallely, professor of medical virology at the University of Manchester.
“However, in this case, the mutations apparently do not render the virus nonviable and may help it adapt to human-to-human transmission,” said Vallely, who was not involved in the study. Newsweek. “It’s just a theory that matches the current evidence, and a lot more work will be needed to see if that’s really what’s happening. I don’t think we can say that the mutations made it more contagious, but maybe they made it more suitable for humans.”
The researchers say their work shows that sequencing the monkeypox viral genome could be precise enough to track the spread of the current outbreak and see how transmission might change. This, in turn, would allow policy makers to introduce measures to curb the spread of monkeypox. Vaccines are already available.
Jeremy Kamil, associate professor of microbiology and immunology at Louisiana State University Health Shreveport, said Newsweek the study as “very impressive” but said it is too early to say for sure whether monkeypox is rapidly evolving until we can rule out the possibility that the virus is circulating and adapting in humans. people “for longer than people realize – perhaps starting in undersampled parts of the world like parts of Africa where monkeypox is endemic.”
Alex Sigal, a virologist at the African Health Research Institute (AHRI) and associate professor at the University of KwaZulu-Natal, who was also not involved in the study, echoed Kamil’s point.
“I think this outbreak was under the radar for a while,” he said. Newsweek. “Certainly, the decrease in immunity because the smallpox vaccine is no longer given could have helped.
“[The findings are] worrying, but we’ll see if this virus continues to spread once people start to be aware of the signs and it breaks out into the general population. It depends on the contact, and unless the spread becomes respiratory, it should be easier to stop it.”
Virus sequencing efforts also confirmed that the viruses studied belonged to a specific type of monkeypox virus known as clade 3, confirming that they were part of the broader West African type as opposed to the Central African type.
The West African version of monkeypox, with a case fatality rate generally below 1%, is much less virulent than the Central African clade 1 version which can cause death in more than 10% of cases, according to the study.